Embodiments of the inventive concept relate generally to photo-electric integrated circuit devices. More particularly, embodiments of the inventive concept relate to on-die optical input/output devices for photo-electric integrated circuit devices and methods of fabricating the on-die optical input/output devices.
An optical device having an optical waveguide can be formed on a silicon-on-insulator (SOI) substrate. The SOI substrate typically comprises a silicon supporting layer, a silicon oxide layer, and a single crystal silicon layer. The silicon oxide layer is used as a lower cladding layer and is formed in advance below the single crystal silicon layer. The optical waveguide can be formed by etching the single crystal silicon layer of the SOI substrate through a photoresist pattern and then forming an upper cladding layer on the SOI substrate to cover a core of the optical waveguide.
The SOI substrate is typically more expensive than a bulk silicon wafer, which can limit its practical use. In addition, it can be difficult to integrate other electronic devices, such as a dynamic random access memory (DRAM), in the same substrate as the optical device formed in the SOI substrate, because the DRAM is typically formed in bulk silicon. Consequently, other electronic devices, such as the DRAM, are commonly manufactured and packaged separately from the optical device having the optical waveguide. This tends to increase the cost and time of manufacturing the optical device and the other electronic devices.